Showstopper - Technical Article - Chevy High Performance Magazine

Adding a Master Power Disc Brake Kit

Today's vintage musclecar packs more power, is driven faster, and most of all, is asked to stop a whole lot quicker than 40 years ago. And as retro as those drums may look through your mag wheels, the original brake system can't be counted on to stop quickly should trouble arise. In other words, a decrease in stopping distance can mean the difference between a close call or some crumbled Chevy fenders.

However, there is good news. Master Power Brakes has a disc brake kit (available for all popular GM musclecars) that can convert your ride from those low-performing and slow-stopping drums to a stop-on-a-dime, four-wheel disc-brake dancer that rivals many new-car braking standards. The kit comes with easy-to-follow instructions and a handy tech line to call, if needed. To see how this installation works, we used a '65 Chevrolet Biscayne that still wore the factory four-wheel drum system. Master Power offers several kits for this application. For ours we chose three of the options, including a front disc brake conversion kit that bolts to the existing drum spindles, a power-operated tandem master cylinder kit complete with the proper proportioning valve, and a rear disc brake kit that bolts on to the stock rearend housing. If you opt to use the GM rear disc brake rotors, you'll need to have your axle flanges turned down to 5 7/8-inch o.d. to gain the needed clearance inside the hub of the new rotors. If you have aftermarket hardened axles, check with the axle manufacturer first.

Whether you own a full-size Chevrolet, Chevelle, Camaro, Nova, or other GM car, chances are there is a Master Power Brakes kit available for your specific application. Hang on as we show you the ins and outs of adding a power four-wheel disc brake system onto our lead-sled Biscayne. We just hope the T3 headlights won't fly out when we hit those new disc brakes hard.

3

The kit we selected for the front of our '65 Biscayne came complete with new disc brake rotors, calipers, adapter brackets, a power brake booster, the master cylinder, including the combination valve with new steel lines, wheel bearings, and hoses.

The stock drum brake hardware, hubs, and backing plates were easily removed. Before we started our install, we measured the wheel-mounting height location on the drum brake hub and compared it to that of the new disc brake hub. We found that the disc brake wheel-mounting position widens the front wheel track 1 inch on each side. To compensate for this, you may want to install the appropriate wheel or tire size to complement the disc brakes and to ensure your tires won't rub.

...and found the larger bracket required the lower inside mounting hole to be reamed out slightly (shown left; original-size hole on right) to allow the bracket to clearance the spindle on its forward lower side. The entire operation took roughly 15 minutes for both brackets.

The new brake rotor is then fitted with new wheel bearings, which we packed with grease, followed by a new inner seal. After the rotor is installed onto the spindle, we spun the rotor while tightening the spindle nut several times. We then backed off the nut just to the next available slot and installed a new cotter key and grease cap. When the rotor is installed properly, there should be a very small amount of endplay felt when the rotor is pushed and pulled laterally on the vehicle.

Next we loaded the front calipers with the new brake pads, slipped them into position, slid the caliper over the rotor onto the mounting holes, and bolted them in place. From there we installed the new brake hoses with the appropriate copper washers.

We then remounted the front wheels and put the car back on the ground. Remember that with the new rotors in place, the wheel mounting positions are moved out 1 inch per side. So make sure you'll have enough tire to fender clearance with the car settled on the ground. If not, different-size tires or rims will give you the necessary clearance.

Our front disc brake kit came with a power brake unit, master cylinder, combination valve, fittings, and metal lines. Since less vacuum will cause a hard pedal, your engine should ideally be able to produce 18 inches of manifold vacuum at idle in Park. Anything less, and you may want to opt for the manual disc kit or install an electric vacuum pump, which is also available from MPB.

The kit we selected for the front of our '65 Biscayne came complete with new disc brake rotors, calipers, adapter brackets, a power brake booster, the master cylinder, including the combination valve with new steel lines, wheel bearings, and hoses.

The stock drum brake hardware, hubs, and backing plates were easily removed. Before we started our install, we measured the wheel-mounting height location on the drum brake hub and compared it to that of the new disc brake hub. We found that the disc brake wheel-mounting position widens the front wheel track 1 inch on each side. To compensate for this, you may want to install the appropriate wheel or tire size to complement the disc brakes and to ensure your tires won't rub.

Next we unbolted the drum brake backing plates from the spindles and disconnected the stock hoses from the steel lines.

Then we attached the two front brake caliper brackets...

...and found the larger bracket required the lower inside mounting hole to be reamed out slightly (shown left; original-size hole on right) to allow the bracket to clearance the spindle on its forward lower side. The entire operation took roughly 15 minutes for both brackets.

Finally we tightened everything in place. Double-check the directions to ensure proper torque is applied onto all bolts and nuts.

The new brake rotor is then fitted with new wheel bearings, which we packed with grease, followed by a new inner seal. After the rotor is installed onto the spindle, we spun the rotor while tightening the spindle nut several times. We then backed off the nut just to the next available slot and installed a new cotter key and grease cap. When the rotor is installed properly, there should be a very small amount of endplay felt when the rotor is pushed and pulled laterally on the vehicle.

Next we loaded the front calipers with the new brake pads, slipped them into position, slid the caliper over the rotor onto the mounting holes, and bolted them in place. From there we installed the new brake hoses with the appropriate copper washers.

Before we installed the front wheels, we made one final inspection for clearance, rotor rotation, and did a once-over on the brake-line installation.

We then remounted the front wheels and put the car back on the ground. Remember that with the new rotors in place, the wheel mounting positions are moved out 1 inch per side. So make sure you'll have enough tire to fender clearance with the car settled on the ground. If not, different-size tires or rims will give you the necessary clearance.

Our front disc brake kit came with a power brake unit, master cylinder, combination valve, fittings, and metal lines. Since less vacuum will cause a hard pedal, your engine should ideally be able to produce 18 inches of manifold vacuum at idle in Park. Anything less, and you may want to opt for the manual disc kit or install an electric vacuum pump, which is also available from MPB.

We first removed the stock single reservoir master, metal line, and power brake booster.

Then we disconnected the stock clevis from the brake pedal and drilled a 3/8-inch hole 1 inch below the original.

With the stock power brake booster removed, the two lower holes must be drilled (reamed) out to accept the four studs on the booster. To precisely locate these holes, we used the supplied paper template and marked the firewall.

The center opening also needs to be reamed at the bottom area , as well as the two lower stud holes.

For four-wheel disc brake applications, this nut, pin, and internal spring must be removed from the combination valve in order to provide the proper front-to-rear bias.

Once removed, you'll need to insert this plug.

After bench-bleeding the master cylinder, we installed the supplied brake lines so one master cylinder outlet goes to the front and the other to the rear, splitting the system in series with the new combination valve. While this may sound confusing, an easy-to-follow schematic is provided that's unique to the master cylinder for your specific kit. The lines from the combination valve to the frame are not included.

After installing the master and booster assembly into the car, we reattached the clevis at the brake pedal and hooked up the brake lines.

Both axles needed to be removed to install the rear disc kit. To do that, the pin and two C-clips must first be removed from the center carrier.

With the drums removed, the axles simply slide out. In order to use the GM rotors, you'll have to turn the stock axle flanges down to 5 7/8-inch o.d. Standard factory-type axles are easily machined on a lathe, but if you're using aftermarket axles, be sure to consult the manufacturer to see if they have heat-treated flanges before attempting to machine them. If they are heat-treated, now's the time to ask the manufacturer for a recommendation.

We removed the metal brake lines to the wheel cylinders, the existing backing plates, and the parking brake cables from under the car.

As shown in this mock-up example, the rear calipers, bleeder screw, and parking brake cable (when mounted on the bracket) should be installed so that they are positioned at the top. The attached parking-brake cables will route to the center of the vehicle, where they can be connected to the existing parking-brake system.

Secure everything tightly and check for frame clearance throughout full frame travel. Rotate the rotor and check for any interference. The rotor should run true. Remember to reinstall the carrier slide pin, bolt, and rearend cover, and add gear oil.

Now make all the final connections and bleed the entire brake system. After the rear wheels are mounted, you'll want to check rear wheel clearance, since the new rotors will space the wheels out about 1/4 inch. Once everything is bled and installed to spec, drive the car easily and test the brake system on a deserted road...

...If your brake pedal is low, check the accompanying tech tip. Finally, once everything is completed, be easy on the brakes for the next several hundred miles to break in the new rotors and seat the pads.

Proportioning valves come in all shapes and sizes and vary considerably depending on the car you are working on in a brake disc conversion, and we have expert tips to help you decide. - Super Chevy Magazine » Read More